Liquid crystal polymer film and laminate comprising the same

ABSTRACT

Provided are a liquid crystal polymer (LCP) film and a laminate comprising the same. The LCP film has a first surface and a second surface opposite each other, and a ratio of a ten-point mean roughness relative to a maximum height (Rz/Ry) of the first surface is from 0.30 to 0.62. By controlling Rz/Ry of at least one surface of the LCP film, the peel strength of the LCP film stacked to a metal foil can be increased, and the laminate comprising the same can still maintain the merit of low insertion loss.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 16/748,846, filed Jan. 22, 2020, which claims thebenefit of Taiwan Patent Application No. 108147226, filed Dec. 23, 2019,each of which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present application relates to a polymer film for a laminate, moreparticularly to a liquid crystal polymer (LCP) film and a laminatecomprising the same.

2. Description of the Prior Arts

The rapid development of mobile communication technology has pushed thetelecom industry to actively develop the fifth generation mobilenetworks, abbreviated as 5G, so as to optimize the performances, such asthe data transmission rate, the response time, and the system capacity,etc. of the fourth generation mobile networks (4G).

Since 5G communication technology uses high-frequency bands for signaltransmission, the higher the frequency of the signal, the greater theinsertion loss. In order to achieve signal transmission usinghigh-frequency bands, it has been known that an LCP film with lowdielectric properties can be chosen to match a metal foil, and they areused to produce a laminate so as to decrease dielectric loss of thesignal transmission.

However, the interfacial adhesion between the LCP film and a metal foilis generally insufficient, so components on a circuit board are prone tobe detached and thus subsequent lamination processes will be seriouslyadversely affected. Therefore, the peel strength between the LCP filmand the metal foil of conventional laminates still needs improvement inorder to develop a laminate that is suitable for 5G products.

SUMMARY OF THE INVENTION

To overcome the shortcomings, the objective of the present applicationis to enhance the peel strength between an LCP film and a metal foil.

To achieve the aforementioned objective, one aspect of the presentapplication provides an LCP film. The LCP film has a first surface and asecond surface opposite each other, and a ratio of a ten-point meanroughness relative to a maximum height (Rz/Ry) of the first surface maybe more than or equal to 0.30 and less than or equal to 0.62.

By controlling the Rz/Ry property of either surface (e.g., the firstsurface) of the LCP film, the adhesion of the LCP film stacked to themetal foil can be increased, thereby enhancing the peel strength betweenthe LCP film and the metal foil. Therefore, the problem such as wiredetachment during subsequent processing of a laminate can be avoided.

In accordance with the present application, in terms of the secondsurface of the LCP film, Rz/Ry thereof may also be more than or equal to0.30 and less than or equal to 0.62. Herein, regardless of whether theLCP film of the present application is laminated with at least one metalfoil through either or both of the first surface and the second surface,the LCP film can possess superior adhesion to the at least one metalfoil, thus improving the peel strength between the LCP film and the atleast one metal foil. Preferably, Rz/Ry of the first surface and/orRz/Ry of the second surface of the LCP film of the present applicationmay also be more than or equal to 0.36 and less than or equal to 0.61.In one of the embodiments, Rz/Ry of the first surface and Rz/Ry of thesecond surface of the LCP film of the present application may be thesame or different. In one of the embodiments, Rz/Ry of the first surfaceand Rz/Ry of the second surface of the LCP film of the presentapplication both fall within the aforementioned ranges.

In accordance with the present application, Rz of the first surface ofthe LCP film may be less than or equal to 2 micrometers (μm).Preferably, Rz of the first surface of the LCP film of the presentapplication may be less than or equal to 1.5 μm; more preferably, Rz ofthe first surface of the LCP film of the present application may be morethan or equal to 0.3 μm and less than or equal to 1.5 μm; even morepreferably, Rz of the first surface of the LCP film of the presentapplication may be more than or equal to 0.3 μm and less than or equalto 1.4 μm; still more preferably, Rz of the first surface of the LCPfilm of the present application may be more than or equal to 0.3 μm andless than or equal to 1.3 μm; yet still more preferably, Rz of the firstsurface of the LCP film of the present application may be more than orequal to 0.35 μm and less than or equal to 1.2 μm; even furtherpreferably, Rz of the first surface of the LCP film of the presentapplication may be more than or equal to 0.39 μm and less than or equalto 1.2 μm. In one of the embodiments, Rz of the first surface and Rz ofthe second surface of the LCP film of the present application may be thesame or different. In one of the embodiments, Rz of the first surfaceand Rz of the second surface of the LCP film of the present applicationboth fall within the aforementioned ranges.

In accordance with the present application, Ry of the first surface ofthe LCP film may be less than or equal to 2.2 μm. In one of theembodiments, Ry of the first surface of the LCP film of the presentapplication may be less than or equal to 2.0 μm; preferably, Ry of thefirst surface of the LCP film of the present application may be morethan or equal to 0.5 μm and less than or equal to 1.8 μm; morepreferably, Ry of the first surface of the LCP film of the presentapplication may be more than or equal to 0.6 μm and less than or equalto 1.6 μm. In one of the embodiments, Ry of the first surface and Ry ofthe second surface of the LCP film of the present application may be thesame or different. In one of the embodiments, Ry of the first surfaceand Ry of the second surface of the LCP film of the present applicationboth fall within the aforementioned ranges.

Preferably, arithmetic average roughness (Ra) of the first surface ofthe LCP film of the present application may be less than or equal to0.09 μm. Herein, applying the LCP film to a laminate can significantlydecrease the insertion loss, so that the laminate comprising the LCPfilm is highly suitable for high-end 5G products.

More preferably, Ra of the first surface of the LCP film of the presentapplication may be more than or equal to 0.02 μm and less than or equalto 0.08 ion; even more preferably, Ra of the first surface may be morethan or equal to 0.02 μm and less than or equal to 0.07 μm; still morepreferably, Ra of the first surface may be more than or equal to 0.02 μmand less than or equal to 0.06 μm. By means of decreasing Ra of thefirst surface of the LCP film, the insertion loss of the laminateincluding the LCP film is further reduced, so that the laminate ishighly suitable for high-end 5G products. In one of the embodiments, Raof the first surface and Ra of the second surface of the LCP film of thepresent application may be the same or different. In one of theembodiments, Ra of the first surface and Ra of the second surface of theLCP film of the present application both fall within the aforementionedranges.

In accordance with the present application, the LCP film may be producedby an LCP resin, which is commercially available or made fromconventional raw materials. In the present application, the LCP resin isnot particularly restricted. For example, aromatic or aliphatic hydroxycompounds such as hydroquinone, resorcin, 2,6-naphthalenediol,ethanediol, 1,4-butanediol, and 1,6-hexanediol; aromatic or aliphaticdicarboxylic acids such as terephthalic acid, isophthalic acid,2,6-naphthalenedicarboxylic acid, 2-chloroterephthalic acid, and adipicacid; aromatic hydroxy carboxylic acids such as 3-hydroxybenzoic acid,4-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, and4′-hydroxy-4-biphenylcarboxylic acid; aromatic amine compounds such asp-phenylenediamine, 4,4′-diaminobiphenyl, naphthalene-2,6-diamine,4-aminophenol, 4-amino-3-methylphenol, and 4-aminobenzoic acid may beused as raw materials to prepare the LCP resin, and the LCP resin isthen used to prepare the LCP film of the present application. In one ofthe embodiments of the present application,6-hydroxy-2-naphthalenecarboxylic acid, 4-hydroxybenzoic acid, andacetyl anhydride (also called acetic anhydride) may be chosen to obtainthe LCP resin, which can be used to prepare the LCP film of the presentapplication. In one of the embodiments, the melting point of the LCPresin may be about 250° C. to 360° C.

In one of the embodiments, a person having ordinary knowledge in the artmay add additives such as, but not limited to, lubricants, antioxidants,electrical insulating agents, or fillers during preparation of the LCPfilm of the present application based on different needs. For example,the applicable additives may be, but are not limited to, polycarbonate,polyamide, polyphenylene sulfide, polyetheretherketone, etc.

In accordance with the present application, the thickness of the LCPfilm is not particularly restricted. For example, the thickness of theLCP film may be more than or equal to 10 μm and less than or equal to500 μm; preferably, the thickness of the LCP film of the presentapplication may be more than or equal to 10 μm and less than or equal to300 μm; more preferably, the thickness of the LCP film of the presentapplication may be more than or equal to 15 μm and less than or equal to250 μm; even more preferably, the thickness of the LCP film of thepresent application may be more than or equal to 20 μm and less than orequal to 200 μm.

To achieve the aforementioned objective, another aspect of the presentapplication also provides a laminate, which comprises a first metal foiland the LCP film. The first metal foil is disposed over the firstsurface of the LCP film.

In one of the embodiments, the laminate of the present application mayfurther comprise a second metal foil, which is disposed over the secondsurface of the LCP film, i.e., the LCP film of the present applicationis sandwiched between the first metal foil and the second metal foil. Inthis embodiment, when the Rz/Ry properties of both of the first surfaceand the second surface the LCP film are controlled at the same time, theadhesion of the LCP film stacked to the first metal foil and theadhesion of the LCP film stacked to the second metal foils are improvedsimultaneously, and thus the peel strength between the LCP film and thefirst metal foil as well as the peel strength between the LCP film andthe second metal foil are enhanced.

In accordance with the present application, “stacking” is not limited todirect contact; further, it also includes indirect contact. For example,in one of the embodiments of the present application, the first metalfoil and the LCP film in the laminate are stacked with each other in adirect contact manner, that is, the first metal foil is disposed on andin direct contact with the first surface of the LCP film. In anotherembodiment of the present application, the first metal foil and the LCPfilm in the laminate are stacked with each other in an indirect contactmanner, that is, the first metal foil is disposed above the LCP film,and the first metal foil and the LCP film are stacked with each other inan indirect contact manner. For example, a connection layer may bedisposed between the first metal foil and the LCP film based ondifferent needs, so that the first metal foil contacts the first surfaceof the LCP film via the connection layer. The material of the connectionlayer may be adjusted according to different needs to providecorresponding functions. For example, the material of the connectionlayer may include nickel, cobalt, chromium, or alloys thereof to providefunctions such as thermal resistance, chemical resistance, or electricalresistance. Similarly, the second metal foil and the LCP film in thelaminate may also be stacked with each other in direct contact orindirect contact. In one of the embodiments of the present application,the stacking manner for the LCP film and the first metal foil and theone for the LCP film and the second metal foil may be the same ordifferent.

In accordance with the present application, the first metal foil and/orthe second metal foil may be, but are not limited to, copper foil, goldfoil, silver foil, nickel foil, aluminum foil, stainless steel foil,etc. In one of the embodiments, the first metal foil and the secondmetal foil are made of different materials. Preferably, the first metalfoil and/or the second metal foil may be copper foil, so that the copperfoil and the LCP film are stacked to form a copper clad laminate (CCL).In addition, the manufacturing method of the first metal foil and/or themanufacturing method of the second metal foil are not particularlyrestricted, as long as the methods do not violate the objective of thepresent application. For example, the metal foil may be produced by, butnot limited to, a roll-to-roll method or an electrodeposition method.

In accordance with the present application, the thickness of the firstmetal foil and/or the second metal foil is not particularly restrictedand can be adjusted based on different needs by a person having ordinaryknowledge in the art. For example, in one of the embodiments, thethickness of the first metal foil and/or the second metal foil mayindependently be more than or equal to 1 μm and less than or equal to200 μm; preferably, the thickness of the first metal foil and/or thesecond metal foil may independently be more than or equal to 1 μm andless than or equal to 40 μm; more preferably, the thickness of the firstmetal foil and/or the second metal foil may independently be more thanor equal to 1 μm and less than or equal to 20 μm; even more preferably,the thickness of the first metal foil and/or the second metal foil mayindependently be more than or equal to 3 μm and less than or equal to 20μm.

In accordance with the present application, surface treatments of thefirst metal foil and/or the second metal foil of the present applicationcan be conducted based on different needs by a person having ordinaryknowledge in the art. For example, the surface treatments may beselected from, but not limited to, roughening treatments, acid-basetreatments, thermal treatments, degreasing treatments, ultravioletirradiation treatments, corona discharge treatments, plasma treatments,primer coating treatments, etc.

In accordance with the present application, the roughness of the firstmetal foil and/or the second metal foil is not particularly restrictedand can be adjusted according to different needs by a person havingordinary knowledge in the art. In one of the embodiments, Rz of thefirst metal foil and/or Rz of the second metal foil may independently bemore than or equal to 0.1 μm and less than or equal to 2.0 μm;preferably, Rz of the first metal foil and/or Rz of the second metalfoil may independently be more than or equal to 0.1 μm and less than orequal to 1.5 μm. In one of the embodiments, Rz of the first metal foiland Rz of the second metal foil may be the same or different. In one ofthe embodiments, Rz of the first metal foil and Rz of the second metalfoil both fall within the aforementioned ranges.

In one of the embodiments, a third metal foil may be additionallyprovided based on different needs by a person having ordinary knowledgein the art. The third metal foil may be the same or different from thefirst metal foil and/or the second metal foil. In one of theembodiments, Rz of the third metal foil may fall within theaforementioned ranges of Rz of the first metal foil and/or Rz of thesecond metal foil.

In one of the embodiments, the laminate may comprise multiple LCP films.Based on the premise of not violating the spirit of the presentapplication, multiple LCP films of the present application and multiplemetal foils, such as the aforesaid first metal foil, second metal foil,and/or third metal foil, may be stacked based on different needs toproduce a laminate having the multiple LCP films and the multiple metalfoils by a person having ordinary knowledge in the art.

In the specification, the terms “ten-point mean roughness (Rz)”,“maximum height (Ry)”, and “arithmetic average roughness (Ra)” aredefined according to JIS B 0601:1994.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, multiple preparation examples are provided to illustrateraw materials used to produce the LCP film of the present application.Multiple examples are further provided to illustrate the implementationof the LCP film and the laminate of the present application, whilemultiple comparative examples are provided as comparison. A personskilled in the art can easily realize the advantages and effects of thepresent application from the following examples and comparativeexamples. The descriptions proposed herein are just preferableembodiments for the purpose of illustrations only, not intended to limitthe scope of the present application. Various modifications andvariations could be made in order to practice or apply the presentapplication without departing from the spirit and scope of the presentapplication.

<LCP Resin>

Preparation Example 1: LCP Resin

A mixture of 6-hydroxy-2-naphthalenecarboxylic acid (700 g),4-hydroxybenzoic acid (954 g), acetyl anhydride (1085 g), and sodiumphosphite (1.3 g) was charged into a 3-liter autoclave and stirred foracetylation at 160° C. for about 2 hours under nitrogen atmosphere atnormal pressure. Subsequently, the mixture was heated to 320° C. at arate of 30° C. per hour, and then under this temperature condition, thepressure was reduced slowly from 760 torr to 3 torr or below, and thetemperature was increased from 320° C. to 340° C. Afterwards, thestirring power and the pressure were increased, and steps of dischargingpolymers, drawing strands, and cutting strands into pellets wereconducted to obtain an LCP resin having a melting point about 265° C.and a viscosity about 60 pascal-seconds (Pa·s) measured at 300° C.(hereinafter referred to as @300° C.).

Preparation Example 2: LCP Resin

A mixture of 6-hydroxy-2-naphthalenecarboxylic acid (440 g),4-hydroxybenzoic acid (1145 g), acetyl anhydride (1085 g), and sodiumphosphite (1.3 g) was charged into a 3-liter autoclave and stirred foracetylation at 160° C. for about 2 hours under nitrogen atmosphere atnormal pressure. Subsequently, the mixture was heated to 320° C. at arate of 30° C. per hour, and then under this temperature condition, thepressure was reduced slowly from 760 torr to 3 torr or below, and thetemperature was increased from 320° C. to 340° C. Afterwards, thestirring power and the pressure were increased, and steps of dischargingpolymers, drawing strands, and cutting strands into pellets wereconducted to obtain an LCP resin having a melting point about 305° C.and a viscosity about 40 Pa·s @300° C.

Preparation Example 3: LCP Resin

A mixture of 6-hydroxy-2-naphthalenecarboxylic acid (540 g),4-hydroxybenzoic acid (1071 g), acetyl anhydride (1086 g), sodiumphosphite (1.3 g), and 1-methylimidazole (0.3 g) was charged into a3-liter autoclave and stirred for acetylation at 160° C. for about 2hours under nitrogen atmosphere at normal pressure. Subsequently, themixture was heated to 320° C. at a rate of 30° C. per hour, and thenunder this temperature condition, the pressure was reduced slowly from760 torr to equal to or less than 3 torr or below, and the temperaturewas increased from 320° C. to 340° C. Afterwards, the stirring power andthe pressure were increased, and steps of discharging polymers, drawingstrands, and cutting strands into pellets were conducted to obtain anLCP resin having a melting point about 278° C. and a viscosity about 45Pa·s @300° C.

LCP Film

Examples 1 to 13 and Comparative Examples 1 to 5: LCP Film

The LCP resin obtained from Preparation Examples 1 to 3 (PE1 to PE3) wasused as raw materials to prepare LCP films of Examples 1 to 13 (E1 toE13) and Comparative Examples 1 to 5 (C1 to C5) by the methods describedbelow.

First, the LCP resin was put into an extruder having a screw diameter of27 millimeters (mm) (manufacturer: Leistritz, model: ZSE27) and heatedto a temperature ranging from 300° C. to 320° C., and then extruded froma T-die of a width of 500 mm with a feeding speed ranging from 3.5kilograms per hour (kg/hr) to 10 kg/hr. The LCP resin was then deliveredto a space between two casting wheels having a temperature ranging fromabout 250° C. to 320° C. and a diameter ranging from about 35centimeters (cm) to 45 cm, extruded with a force about 20 kilonewtons(kN) to 60 kN, and then transferred to a cooling wheel for cooling atroom temperature to obtain an LCP film having a thickness of 50 μm.Herein, the casting wheels were spaced about 1 mm to 50 mm from theT-die.

The processes of Examples 1 to 13 differ from those of ComparativeExamples 1 to 5 in the kind of the LCP resin, the distance from theT-die to the surfaces of the casting wheels, the feeding speed, and theextrusion temperature. The parameters of Examples 1 to 13 andComparative Examples 1 to 5 are respectively listed in Table 1 below.

TABLE 1 parameters of LCP films of Examples 1 to 13 and ComparativeExamples 1 to 5 Parameters Sam- Distance from Feeding Extrusion ple LCPT-die to casting Speed Temp. No. Resin wheels (mm) (kg/hr) (° C.) E1 PE120 7.5 310 E2 PE1 20 7.5 315 E3 PE1 20 7.5 320 E4 PE1 20 6.5 290 E5 PE120 8.5 310 E6 PE1 20 8.5 315 E7 PE1 20 8.5 320 E8 PE1 20 5.5 310 E9 PE220 5.5 315 E10 PE3 20 5.5 320 E11 PE1 20 6.5 310 E12 PE2 20 6.5 315 E13PE3 20 6.5 320 C1 PE1 20 7.5 300 C2 PE1 20 8.5 290 C3 PE1 5 6.5 310 C4PE1 5 5.5 320 C5 PE1 5 7.5 315

The above-mentioned preparation method of LCP film is only used toexemplify implementation of the present application. A person havingordinary knowledge in the art may also use conventional methods such asa laminate extension method and an inflation method to prepare an LCPfilm.

In one of the embodiments, after the LCP resin was extruded from theT-die, the LCP resin might be delivered with two high-temperatureresistant films to a space between two casting wheels to form athree-layered laminate based on needs by a person having ordinaryknowledge in the art. The two high-temperature resistant films weredetached from the LCP resin at room temperature to obtain the LCP filmof the present application. The high-temperature resistant film may beselected from, but not limited to, poly(tetrafluoroethene) (PTFE) film,polyimide (PI) film, and poly(ether sulfone) (PES) film.

In addition, post treatments for the obtained LCP film may be conductedbased on different needs by a person having ordinary knowledge in theart. The post treatments may be, but are not limited to, polishing,ultraviolet irradiation, plasma, etc. For the plasma treatment, it maybe applied with a plasma operated with a power of 1 kW under nitrogen,oxygen, or air atmosphere at a reduced or normal pressure based ondifferent needs, but is not limited thereto.

Test Example 1: Roughness of LCP Films

In this test example, the LCP films of Examples 1 to 13 and ComparativeExamples 1 to 5 were used as test samples. The surface morphology imagesof the test samples were each taken using a laser microscope(manufacturer: Olympus, model: LEXT OLS5000-SAF, objective lens:MPLAPON-50×LEXT) with an objective lens having a magnification power of50×, 1× optical zoom, and a 405 nanometers (nm) wavelength of lightsource at a temperature of 24±3° C. and a relative humidity of 63±3%.Ra, Ry, and Rz of either surface of the test samples were measuredaccording to JIS B 0601:1994 using an evaluation length of 4 mm and acutoff value (λc) of 0.8 mm. The results of the test samples are listedin Table 2 below.

Examples 1A to 13A: Laminates

Laminates of Examples 1A to 13A (E1A to E13A) and Comparative Examples1A to 5A (C1A to C5A) were produced from the LCP films of Examples 1 to13 as well as Comparative Examples 1 to 5 and commercially availablecopper foils. The product descriptions of the commercially availablecopper foils are provided as follows:

Copper foil 1: CF-T49A-HD2, purchased from FUKUDA METAL FOIL & POWDERCO., LTD., Rz: about 1.2 μm;

Copper foil 2: CF-H9A-HD2, purchased from FUKUDA METAL FOIL & POWDERCO., LTD., Rz: about 1.0 μm;

Copper foil 3: 3EC-M2S-HTE-SP2, purchased from MITSUI MINING & SMELTINGCO., LTD., Rz: about 1.1 μm; and

Copper foil 4: TQ-M7-VSP, purchased from MITSUI MINING & SMELTING CO.,LTD., Rz: about 1.1 μm.

The kind of the LCP film and the kind of the copper foil used for eachof the laminates of Examples 1A to 13A and Comparative Examples 1A to 5Awere listed in Table 2, and each of the laminates was produced asfollows.

The LCP film having a thickness about 50 μm and two identical copperfoils each having a thickness about 12 μm were each first cut to size of20 cm*20 cm. The LCP film was then sandwiched between the two copperfoils to form a laminated structure. The laminated structure wassubjected to a pressure of 5 kilograms per square centimeter (kg/cm²)for 60 seconds at 180° C., followed by a pressure of 20 kg/cm² for 25minutes (min) at 300° C., and then cooled to room temperature to obtaina laminate.

Herein, the lamination method for the laminates is not particularlyrestricted. A person having ordinary knowledge in the art may useconventional techniques such as a wire lamination or a surfacelamination to conduct the lamination process. A laminator applicable tothe present application may be, but is not limited to, an intermittenthot-press machine, a roll-to-roll wheeling machine, a double belt pressmachine, etc. According to different needs, a person having ordinaryknowledge in the art can also align the LCP film with the copper foilsto form a laminated structure, which may then be processed with surfacelamination comprising a heating step and a pressing step.

In another embodiment, a metal foil, such as a copper foil, on an LCPfilm may be formed through sputtering, electroplating, chemical plating,evaporation deposition, etc. based on different needs by a person havingordinary knowledge in the art. Or, a connection layer, such as a gluelayer, a nickel layer, a cobalt layer, a chromium layer, or an alloylayer thereof, may be formed between an LCP film and a metal foil basedon different needs by a person having ordinary knowledge in the art.

Test Example 2: Peel Strength of Laminates

The peel strength of the laminates was measured according to IPC-TM-650No.: 2.4.9. The laminates of Examples 1A to 13A and Comparative Examples1A to 5A were each cut to size of a length about 228.6 mm and a widthabout 3.2 mm as etched specimens. Each etched specimen was placed at atemperature of 23±2° C. and a relative humidity of 50±5% for 24 hours toreach stabilization. Subsequently, each etched specimen was adhered to aclamp of a testing machine (manufacturer: Hung Ta Instrument Co., Ltd.,model: HT-9102) with a double faced adhesive tape. Each etched specimenwas then peeled from the clamp with a force at a peel speed of 50.8mm/min, and the value of the force during the peeling process wascontinuously recorded. Herein, the force should be controlled within arange of 15% to 85% of the bearable force of the testing machine, thepeeling distance from the clamp should be at least more than 57.2 mm,and the force for the initial distance of 6.4 mm was neglected and notrecorded. The results are shown in Table 2.

TABLE 2 roughness of LCP films of Examples 1 to 13 and ComparativeExamples 1 to 5, and sample number of copper foil and peel strength oflaminates of Examples 1A to 13A and Comparative Examples 1A to 5A LCPFilm Laminate Sample Ra Rz Sample Copper Foil Peel Strength No. Rz/Ry(μm) (μm) No. No. (kN/m) E1 0.483 0.029 0.506 E1A Copper Foil 1 0.68 E20.548 0.034 0.534 E2A Copper Foil 1 0.60 E3 0.606 0.041 0.826 E3A CopperFoil 1 0.58 E4 0.422 0.092 0.793 E4A Copper Foil 1 0.70 E5 0.361 0.0571.186 ESA Copper Foil 2 1.44 E6 0.476 0.026 0.390 E6A Copper Foil 2 1.38E7 0.553 0.036 0.735 E7A Copper Foil 2 1.30 E8 0.492 0.031 0.856 E8ACopper Foil 3 0.53 E9 0.532 0.032 0.547 E9A Copper Foil 3 0.48 E10 0.5660.033 0.602 E10A Copper Foil 3 0.45 E11 0.495 0.037 0.864 E11A CopperFoil 4 0.83 E12 0.530 0.035 0.609 E12A Copper Foil 4 0.85 E13 0.5670.037 0.591 E13A Copper Foil 4 0.78 C1 0.829 0.088 1.562 C1A Copper Foil1 0.56 C2 0.896 0.122 1.839 C2A Copper Foil 1 0.53 C3 0.685 0.043 0.717C3A Copper Foil 1 0.52 C4 0.632 0.057 1.049 C4A Copper Foil 1 0.50 C50.814 0.034 0.442 C5A Copper Foil 2 1.18

Test Example 3: Insertion Loss of Laminates

The laminates of Examples 1A to 13A and Comparative Examples 1A to 5Awere each cut to size of a length about 100 mm, a width about 140 mm,and a resistance about 50 Ohm (Ω) as strip line specimens. The insertionloss of the strip line specimens was measured under 10 GHz by amicrowave network analyzer (manufacturer: Agilent Technologies, Ltd.,model: 8722ES) including a probe (manufacturer: Cascade Microtech,model: ACP40-250).

The LCP films of Examples 1 to 7 as well as Comparative Examples 1 to 5were chosen as examples to laminate with the commercially availablecopper foils, the laminates of Examples 1A to 7A and ComparativeExamples 1A to 5A were prepared to evaluate insertion loss, and theresults are listed in Table 3 below.

TABLE 3 descriptions of LCP films and copper foils used for laminates ofExamples 1A to 7A and Comparative Examples 1A to 5A and insertion lossof the laminates Laminate LCP Film Insertion Sample Ra Rz Sample CopperFoil Loss No. Rz/Ry (μm) (μm) No. No. (dB) E1 0.483 0.029 0.506 E1ACopper Foil 1 −2.9 E2 0.548 0.034 0.534 E2A Copper Foil 1 −2.9 E3 0.6060.041 0.826 E3A Copper Foil 1 −2.9 E4 0.422 0.092 0.793 E4A Copper Foil1 −3.1 E5 0.361 0.057 1.186 E5A Copper Foil 2 −2.9 E6 0.476 0.026 0.390E6A Copper Foil 2 −2.8 E7 0.553 0.036 0.735 E7A Copper Foil 2 −2.9 C10.829 0.088 1.562 C1A Copper Foil 1 −3.1 C2 0.896 0.122 1.839 C2A CopperFoil 1 −3.1 C3 0.685 0.043 0.717 C3A Copper Foil 1 −3.0 C4 0.632 0.0571.049 C4A Copper Foil 1 −2.9 C5 0.814 0.034 0.442 C5A Copper Foil 2 −2.9

Discussion on Test Results

As shown in Table 2 above, Rz/Ry of either surface of the LCP film ofeach of Examples 1 to 13 was controlled within the range between morethan or equal to 0.30 and less than or equal to 0.62, so the laminates(Examples 1A to 13A) produced from such LCP films and variouscommercially available copper foils with low roughness all exhibitedhigh peel strength. In addition, as shown in Table 3 above, take theresults of Examples 1A to 7A as examples, when Rz/Ry of either surfaceof the LCP films was controlled within the range between more than orequal to 0.30 and less than or equal to 0.62, the insertion loss of thelaminates of Examples 1A to 7A was modulated to be −3.1 dB or less.

The results of Table 2 were further analyzed. For laminates havingCopper foil 1, the laminates with the LCP films of Examples 1 to 4 allexhibited higher peel strength than the ones with the LCP films ofComparative Examples 1 to 4. Similarly, for laminates having Copper foil2, the laminates with the LCP films of Examples 5 to 7 all exhibitedhigher peel strength than the one with LCP film of Comparative Example5. Clearly, the peel strength of the laminates produced from the LCPfilms of the present application is certainly improved, so the laminatesare suitable for processing and problems of component detachment will beeffectively avoided.

Furthermore, from the test results of the laminates of Examples 1A to7A, when either surface of the LCP film has Rz/Ry of more than or equalto 0.30 and less than or equal to 0.62 as well as Ra of less than orequal to 0.09, the peel strength of the laminates (Examples 1A to 3A and5A to 7A) having the LCP film and copper foils was enhanced, and theinsertion loss of the laminates was further reduced to −2.9 dB or less.Thus, the laminates that exhibited high peel strength as well as lowinsertion loss were provided.

In summary, by controlling Rz/Ry of at least one surface of the LCP filmthat is more than or equal to 0.30 and less than or equal to 0.62, thepeel strength of the LCP film stacked to metal foils can be specificallyimproved. In addition, by controlling Ra and Rz/Ry of at least onesurface of the LCP film, the laminate having the LCP film not only hasimproved peel strength but also has reduced insertion loss. Therefore,the laminate of the present application is highly suitable for high-end5G products.

Even though numerous characteristics and advantages of the presentapplication have been set forth in the foregoing description, togetherwith details of the structure and features of the present application,the disclosure is illustrative only. Changes may be made in the details,especially in matters of shape, size, and arrangement of parts withinthe principles of the present application to the full extent indicatedby the broad general meaning of the terms in which the appended claimsare expressed.

What is claimed is:
 1. A liquid crystal polymer film, comprising a firstsurface and a second surface opposite each other, a ratio of a ten-pointmean roughness relative to a maximum height of the first surface beingmore than or equal to 0.36 and less than or equal to 0.61, and themaximum height of the first surface being more than or equal to 1.1 μmand less than or equal to 2.2 μm.
 2. The liquid crystal polymer film asclaimed in claim 1, wherein an arithmetic average roughness of the firstsurface is less than or equal to 0.09 μm.
 3. The liquid crystal polymerfilm as claimed in claim 2, wherein the arithmetic average roughness ofthe first surface is more than or equal to 0.02 μm and less than orequal to 0.08 μm.
 4. The liquid crystal polymer film as claimed in claim1, wherein the ten-point mean roughness of the first surface is lessthan or equal to 2 μm.
 5. The liquid crystal polymer film as claimed inclaim 4, wherein the ten-point mean roughness of the first surface isless than or equal to 1.5 μm.
 6. The liquid crystal polymer film asclaimed in claim 1, wherein the maximum height of the first surface ismore than or equal to 1.6 μm and less than or equal to 2.2 μm.
 7. Theliquid crystal polymer film as claimed in claim 1, wherein a ratio of aten-point mean roughness relative to a maximum height of the secondsurface is more than or equal to 0.30 and less than or equal to 0.62. 8.The liquid crystal polymer film as claimed in claim 2, wherein a ratioof a ten-point mean roughness relative to a maximum height of the secondsurface is more than or equal to 0.30 and less than or equal to 0.62. 9.The liquid crystal polymer film as claimed in claim 3, wherein a ratioof a ten-point mean roughness relative to a maximum height of the secondsurface is more than or equal to 0.30 and less than or equal to 0.62.10. The liquid crystal polymer film as claimed in claim 4, wherein aratio of a ten-point mean roughness relative to a maximum height of thesecond surface is more than or equal to 0.30 and less than or equal to0.62.
 11. The liquid crystal polymer film as claimed in claim 5, whereina ratio of a ten-point mean roughness relative to a maximum height ofthe second surface is more than or equal to 0.30 and less than or equalto 0.62.
 12. The liquid crystal polymer film as claimed in claim 6,wherein a ratio of a ten-point mean roughness relative to a maximumheight of the second surface is more than or equal to 0.30 and less thanor equal to 0.62.
 13. The liquid crystal polymer film as claimed inclaim 7, wherein an arithmetic average roughness of the second surfaceis less than or equal to 0.09 μm.
 14. The liquid crystal polymer film asclaimed in claim 8, wherein an arithmetic average roughness of thesecond surface is less than or equal to 0.09 μm.
 15. The liquid crystalpolymer film as claimed in claim 9, wherein an arithmetic averageroughness of the second surface is less than or equal to 0.09 μm. 16.The liquid crystal polymer film as claimed in claim 10, wherein anarithmetic average roughness of the second surface is less than or equalto 0.09 μm.
 17. The liquid crystal polymer film as claimed in claim 11,wherein an arithmetic average roughness of the second surface is lessthan or equal to 0.09 μm.
 18. The liquid crystal polymer film as claimedin claim 12, wherein an arithmetic average roughness of the secondsurface is less than or equal to 0.09 μm.
 19. A laminate, comprising afirst metal foil and the liquid crystal polymer film as claimed in claim1, the first metal foil disposed over the first surface of the liquidcrystal polymer film.
 20. The laminate as claimed in claim 19, whereinthe laminate comprises a second metal foil, and the second metal foil isdisposed over the second surface of the liquid crystal polymer film.